Exterior Window Sills

Protect your masonry and enhance your windows with prestigious, high-density composite sills meticulously designed to deflect water and resist freeze-thaw cycles.

These high-performance profiles offer the authentic look of limestone without the structural weight of stone.

Achieve a permanent, maintenance-free masonry aesthetic with the enduring durability of advanced modern engineering.

Engineered for superior drainage and zero rot, our composite sills outperform traditional wood and masonry. Compare our technical material science against market alternatives here.

Georgian-style red brick home featuring elegant white exterior composite window and door trim mouldings, including a grand portico with Doric columns and matching window pediments.

Exterior Window Sills Specifications

Composite Durability

Engineered with a high-density EPS core and polymer-modified cement coating for 100% moisture and rot resistance.

Ultra-lightweight

Weighing 90% less than traditional pre-cast concrete, our trims eliminate the need for structural wall reinforcement.

Zero Maintenance

An insect-proof and weather-resistant alternative to wood and PVC that requires no regular painting or sealing.

Zero-Joint Expansion

Advanced cementitious finish prevents splitting and warping, ensuring seamless joints across all exterior facades.

 
The Benjamin 3-3/8 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Aery: 3-3/8 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Cedar: 4 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Deevale: 4 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Regatta: Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Pelmo: 4-7/8 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Ashley: 5-1/4 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Fenelon: 5-1/2 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Geraldine: 5-5/8 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings by Mouldex Composites
 
The Helen: 6 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Tessa: 6 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Charlotte 6-1/8 inch Composite Exterior Window Sill - Premium cement coated foamcore moldings only by Mouldex Composites
 
The Jenette: 6-11/16 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings by Mouldex Composites
 
The Keswick: 6-11/16 inches Composite Exterior Window Sill - Premium cement coated foamcore moldings by Mouldex Composites
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Mouldex Exterior Composite Engineering & Performance

Exterior architectural mouldings, whether used for window trim, sills, or cornices, play a dual role in both aesthetic enhancement and building protection. At Mouldex, we manufacture a proprietary composite solution designed to solve the inherent failures of traditional masonry and wood materials.

1. The Evolution of Foamcore

Mouldex profiles represent a generational leap in material science. We utilize a High-Density Expanded Polystyrene (EPS) core, wrapped in an alkali-resistant fiberglass mesh and encapsulated in a proprietary polymer-modified cement shield. This creates an inorganic, durbale exterior that is 100% moisture-proof and impact-resistant, engineered to outperform traditional foamcore, pre-cast, wood/MDF, and PVC.

2. Versatile Substrate Compatibility

Unlike traditional trims designed for a single wall type, Mouldex is engineered for Universal Compatibility. Our adhesive-based bonding technology is optimized for a permanent, structural hold on Brick, Stone, Stucco, Vinyl/Siding, and ICF. This eliminates the 0.00003 thermal expansion gaps found in PVC and the moisture rot common in Wood and MDF.

3. Unmatched Customization & Arches

Where rigid materials like PVC and wood fail, Mouldex excels. Our Bespoke Customization allows us to manufacture precision-cut Arches, Full Circles, Ovals, and Ellipticals to match any architectural radius. Utilizing advanced CNC technology, we can replicate historical profiles or create modern shapes with a 7–10 days.

4. Timestone Look Without the Weight

Traditional pre-cast concrete requires expensive structural reinforcement and heavy machinery. Mouldex provides an indistinguishable masonry aesthetic at 1/10th the weight. This Weight Efficiency eliminates the need for cranes or wall-load upgrades, typically providing a 75% total cost savings over stonecast products.

5. Engineered for Freeze-Thaw Cycles

Our proprietary coating is the definitive choice for the Northern US and Canadian climates. While GFRC and fiberglass alternatives often crack under thermal stress, Mouldex is engineered for Zero-Joint Expansion, maintaining its structural integrity through extreme temperature swings.

6. Pro-Grade, Fast-Track Installation

Our Nail-less Installation system utilizes high-bond architectural masonry adhesives. This prevents the building envelope from being compromised by thousands of nail holes and eliminates the risk of rusting fasteners bleeding through your finish over time. For larger shapes, we utilize a rear attachment mechanism for stability and safety.

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